50mm Ceramic Hybrid Rear Axle Bearing - 50mm Ceramic Hybrid Rear Axle Bearing 50mm x 80mm x 36.5mm rear axle bearing Ceramic Hybrid Bearings have Steel races and Ceramic Balls. In ball form, ceramic is harder than steel and because ceramic balls are non-porous they are virtually frictionless and capable of spinning faster and with less drag than steel balls as well as being more durable.